Abstract：
OBJECTIVE: To investigate the feasibility of constructing new geometric parameters that correlate well with dosimetric parameters.
METHODS: 100 rectal cancer patients were enrolled. The targets were identified manually, while the organs at risk (bladder, small bowel, left and right femoral heads) were segmented both manually and automatically. The radiotherapy plans were optimized according to the automatically contoured organs at risk. Forty cases were randomly selected to establish the relationship between dose and distance for each organ at risk, termed \"dose-distance curves,\" which were then applied to the new geometric parameters. The correlation between these new geometric parameters and dosimetric parameters was analyzed in the remaining 60 test cases.
RESULTS: The \"dose-distance curves\" were similar across the four organs at risk, exhibiting an inverse function shape with a rapid decrease initially and a slower rate at a later stage. The Pearson correlation coefficients of new geometric parameters and dosimetric parameters in the bladder, small intestine, and left and right femur heads were 0.96, 0.97, 0.88, and 0.70, respectively.
CONCLUSIONS: The new geometric parameters predicated on \"distance from the target\" showed a high correlation with corresponding dosimetric parameters in rectal cancer cases. It is feasible to utilize the new geometric parameters to evaluate the dose deviation attributable to automatic segmentation.
METHODS: 100 rectal cancer patients were enrolled. The targets were identified manually, while the organs at risk (bladder, small bowel, left and right femoral heads) were segmented both manually and automatically. The radiotherapy plans were optimized according to the automatically contoured organs at risk. Forty cases were randomly selected to establish the relationship between dose and distance for each organ at risk, termed \"dose-distance curves,\" which were then applied to the new geometric parameters. The correlation between these new geometric parameters and dosimetric parameters was analyzed in the remaining 60 test cases.
RESULTS: The \"dose-distance curves\" were similar across the four organs at risk, exhibiting an inverse function shape with a rapid decrease initially and a slower rate at a later stage. The Pearson correlation coefficients of new geometric parameters and dosimetric parameters in the bladder, small intestine, and left and right femur heads were 0.96, 0.97, 0.88, and 0.70, respectively.
CONCLUSIONS: The new geometric parameters predicated on \"distance from the target\" showed a high correlation with corresponding dosimetric parameters in rectal cancer cases. It is feasible to utilize the new geometric parameters to evaluate the dose deviation attributable to automatic segmentation.
摘要：
目的：研究构建与剂量学参数密切相关的新几何参数的可行性。
方法：纳入100例直肠癌患者。目标是手动识别的，而处于危险中的器官(膀胱，小肠,左右股骨头）进行手动和自动分割。根据自动轮廓的危险器官优化了放射治疗计划。随机选择40例，建立每个危险器官的剂量和距离之间的关系，称为“剂量-距离曲线”，然后将其应用于新的几何参数。在其余60个测试案例中分析了这些新的几何参数与剂量学参数之间的相关性。
结果：四个危险器官的“剂量-距离曲线”相似，表现出反函数形状，最初迅速下降，后期速度较慢。膀胱中新的几何参数和剂量学参数的皮尔逊相关系数，小肠,左、右股骨头分别为0.96、0.97、0.88、0.70。
结论：在直肠癌病例中，以“距目标距离”为基础的新几何参数与相应的剂量学参数高度相关。利用新的几何参数来评估归因于自动分割的剂量偏差是可行的。
方法：纳入100例直肠癌患者。目标是手动识别的，而处于危险中的器官(膀胱，小肠,左右股骨头）进行手动和自动分割。根据自动轮廓的危险器官优化了放射治疗计划。随机选择40例，建立每个危险器官的剂量和距离之间的关系，称为“剂量-距离曲线”，然后将其应用于新的几何参数。在其余60个测试案例中分析了这些新的几何参数与剂量学参数之间的相关性。
结果：四个危险器官的“剂量-距离曲线”相似，表现出反函数形状，最初迅速下降，后期速度较慢。膀胱中新的几何参数和剂量学参数的皮尔逊相关系数，小肠,左、右股骨头分别为0.96、0.97、0.88、0.70。
结论：在直肠癌病例中，以“距目标距离”为基础的新几何参数与相应的剂量学参数高度相关。利用新的几何参数来评估归因于自动分割的剂量偏差是可行的。
